1. Field of the Invention
The present invention relates to an optical assembly and more specifically to a transceiver assembly which is used for receiving or transmitting optical signals.
2. The Related Art
An optical transceiver module is an important part of an optical communication system. The optical transceiver requires an optical assembly for receiving or transmitting optical signals. The optical assembly consists of many parts which must have precise relative orientation with respect to each other. This complicates the assembling process of the optical assembly. Thus a variety of methods have been developed for manufacturing the optical assembly.
Heat cured epoxy is one of the methods for assembling the optical assembly. The optical assembly includes a support member and a cap member, wherein the support member has a first surface, and the cap member has a corresponding and matching second surface. To assemble, the cap member and the support member are held by an aligning apparatus which is adjusted to have the members in perfect alignment. The members are brought together with the first surface and the second surface mating each other. Heat cured epoxy is applied between the surfaces. Heat is then applied to cure the epoxy by placing the aligning apparatus and the members in a heating oven.
Since it is difficult to have a uniform heating result on the members, the members may displace with respect to each other during the heating process, deteriorating the alignment between the members. Furthermore, unexpected contacts or impacts may occur on the aligning apparatus when it is moved into the heating oven. Such contact or impact may cause misalignment between the members.
Besides the above drawbacks, this method is not suitable for single-mode fiber transmission system. A single-mode optic fiber has a core with a diameter of only 6-10 xcexcm. An offset of 0.5 xcexcm between the members will significantly affect the system.
U.S. Pat. No. 4,969,702 (See FIG. 1) teaches a different method. As shown in FIG. 1, a laser diode 12 is positioned in a support member 14. A focusing member 16, such as a gradient index lens having a planar surface and an opposing convex surface, is positioned with respect to he laser diode 12 such that an output beam from the laser diode 12 passes through the lens 16. A cap member 18 which defines an aperture 22 for receiving a ferrule 26 in which a fiber optic cable 24 is retained is attached to the support member 4 with a mounting surface 20 of the cap member 18 in contact with the support member 14. The relative position between the cap member 18 and the support member 14 is adjusted by aligning apparatus to have the aperture 22 of cap member 18 in alignment with the lens 16. A UV (ultraviolet) cured epoxy is applied between the cap member and the support member so that when the assembly is exposed to UV light, the epoxy is cured and thus fixes the cap member to the support member.
To allow the epoxy to be exposed to the UV, at least one of the members must be transparent. This limits the selection of the material. Furthermore, to avoid blocking UV light, a special design of the aligning apparatus is required. This increases the cost of design and manufacture.
Another method of assembling the optical assembly is disclosed in U.S. Pat. No. 5,073,047 (See FIG. 2). The optical assembly shown in FIG. 2 includes a light source 15 retained in a holder 19, a housing 17 and a receptacle 1. The holder 19 is fusion-welded to the housing 17 by a laser beam. A positional adjustment is performed to align the housing 17 with respect to the receptacle 1. The aligned housing 17 and receptacle 1 are also solidly welded together by means of a laser beam. The cost for performing laser welding is high.
Instant glue is also often employed to attach parts of an optic assembly together due to its low cost. After a positional adjustment is performed between a support member and a cap member by means of an aligning apparatus, the instant glue is applied on the interface between the cap member and the support member. The members are fixed together when the instant glue is cured. The method suffers a non-uniform curing result of the glue because the glue is cured by being contacted with steam and it is hard to control the distribution of steam in a given space. This may cause displacements of the members with respect to each other, resulting in misalignment.
In view of the above, an optical assembly which is assembled easily and has a precise relative orientation is required.
In view of above described problems of the prior art, it is an object of the present invention to provide an optical assembly which can be assembled easily and effectively.
Another object of the present invention is to provide an optical assembly having a precise relative orientation.
To achieve the above objects, the present invention provides a method of assembling an optical assembly using a heat cured epoxy. The optical assembly includes a support member and a receptacle. The support member has a first junction surface and the receptacle has a second junction surface. An electrical heating wire is positioned in the support member proximate the first surface. After having the members in perfect alignment, a heat cured epoxy is applied between the first and second junction surface. The epoxy is cured by heat generated by the heating wire thereby securing the receptacle to the support member.